A local-area network (LAN) is a computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance often spanning an area greater than either LAN via telephone lines, coaxial cable, optical fiber, free-space optics and radio waves. A system of LANs connected in this way is commonly referred to as a wide-area network (WAN).
Optical modules are used in applications requiring digital optical transmission such as SONET/SDH, 10 Gigabit Ethernet, Fibre Channel and DWDM running across metro access networks, wide area networks, access networks, storage area networks, and local area networks.
Optical modules integrate components used in the transmission and reception of optical signals into a single packaged subsystem. Makers of optical networking systems find optical modules attractive, because the highly integrated packaging approach can cut several months of system development and manufacturing time, consume less power and increase port densities over board-level solutions built from discrete components. But with so much functionality in one module, timely and sufficient component supply becomes even more essential for successful system delivery. Multi-source agreement (MSA) developed so systems vendors can feel more confident about getting the components they need and being able to incorporate them without costly and time-consuming system redesigns. Further with MSA, system vendors can concentrate on system architecture and not optical research and development. Optical modules can be purchased off the shelf from a choice of several suppliers.
A typical optical module 1100, as shown in FIG. 11, is composed of a: laser 1101; laser driver (LD) 1102; photo detector (PD) 1103; transimpedance amplifier (TIA) 1104; limiting amplifier (LA) 1105 and sometimes physical-layer devices 1108 such as a mux/demux with associated clock multiplier unit (CMU) and clock data recovery (CDR) functions in a serializer 1109 and deserializer 1110. A typical optical module 1100 has dual optical fibers for reception 1106 and transmission 1107 of signals and can have serial or parallel input 1111 and output 1112 pins. Optical modules have several levels of integration as shown in FIG. 12. Optical modules that contain only the optical-electrical and electrical-optical (o-e/e-o) components 1204, such as a laser and photo detector, are labeled discrete 1202. Optical modules that contain (o-e/e-o) 1204 and hi speed integrated circuits 1205 such as LD, TIA and LA are called transceivers 1201. Optical modules that contain (o-e/e-o) 1204, hi speed integrated circuits 1205 and Mux/Demux devices 1206 are called transponders 1200. Mux/Demux 1206 devices contain CDR and CMUs. Optical modules are ultimately connected with various interfaces to Framers and Media Access Control (MAC) devices 1207 as shown in FIG. 12.
In FIG. 13, the evolution of MSA 10 Gb/s optical modules is shown. Beginning with discrete components, followed by 300pin, XENPAK, X2, and XPAK transponders and finally with XFP transceivers. The evolution of optical modules has been to reduce the size, power, and number of components in optical modules for the purpose of increasing port densities. The very nature of the intent of the invention is contrary to the evolution of MSA 10 Gb/s optical modules in that an increase in power and number of components result while enabling point-to-multipoint networks.